Method of making fluid-heating element



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June 17, 1-930. 'w. F. KEENAN, JR 1,764,174

METHOD OF MAKING FLUID HEATING ELEMENT Original Filed March 23, 1927 I I96. 1/. INVENTOR.

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A TTORNEY Patented June 17, i

uNrrEn STATES PATENT OFFICE WALTER F. KEENAN, 33., OF PELHAM, NEW YORK, ASSIGNOR TO FOSTER WHEELER CORPORATION, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK METHOD OF MAKING FLU ID-HEATING' ELEMENT Original application filed March 23, 1927, Serial No. 177,796. Divided and this application filed Time 18', 1928. Serial No. 285,625.

provide an improved method of The present invention relates to fluid heating elements adapted for use in superheating steam and in heating oil or for other uses by the absorption of radiant heat from a highl heated combustion chamber or other big temperature source of radiant heat. Elements of this type now in use have relatively massive walls to insure proper strength and desirable heat conducting properties. Heretofore'massive walled radiant heat absorbing elements have been made by shrinking massive blocks of cast iron on wrought steel tubing or by forming the elements of cast steel. The first method is objectionable because of the resistance to heat flow across the joints between the cast iron blocks and the innersteel tubes upon which they are shrunk and also because the joints become loose under the severe conditions of use. The method of making the elements of vcast'steel 'is objectionable because of the unduly high cost of production involved in forming one-piece elements of the required length or of uniting several cast steel sections to secure the resufiiciently smooth and uniform to avoidobjectionable friction loss and pressure drop 1s practically impossible.

The object of my present invention is to roducing radiantheat absorbing elements 0 this type which consists in subjecting a thick walled seamless tube blank to a series of welding and forging operations of the character hereinafter described.

The various features of novelty which characterize my invention are pointed out with particularity in the claims annexed to and forming a part of this specification. For a better understanding of the invention, however, its advantages and specific objects attained with its use, reference should be had to the accompanying drawings and descriptive matter in which I have illustrated and described preferred embodiments of my invention.

Of the drawings:

Fig. 1 is an elevation of an element constructed in accordance with the present invention;

Fig. 2 is a section-on the line 2-2 of Fig.

Fig. 11 is an elevation of an element of modified form.

The cross section of the body portion of the finished element A shown in Figs. 1, 2, 3 and 4, is rectangular in form,except' that it is more or less rounded at its corners and the element wall is of approximately uniform thickness, except as it is thickened adjacent the corners of the element. At each end A, the element is enlarged, with a corresponding enlargement of the end portions of the channel A in the element.

In the particular construction illustrated a lateral opening A is formed in the wall of each enlarged end portion A at the rear side of the element; that is, at the side opposite the heat absorbing face of the element. The end connections B communicate with the channel a in the element A through the openings A in which the end connections B are ordinarily expanded to secure them in place and insure tight joints. Tostrengthe'n the joints between the end connections B and the element A, the'rear walls of the end portions-A of the latter are thickened ordinarily and as illustrated by welding ad or ring-like parts C to the element. he welding operation is preferably carried out by means of an acetylene torch and results in the formation of a fillet of the welding metal D integrally connected to the element and pad C at the outer edge of each welded 'oint.

1 When formed as' hereinafter described, each end wall of the portion of the element formed by the tubular blank contains a saucer-like concavity A usually communi-.

eating at its bottom with the passage 0 through a small opening A which may be more or less irregular. The cavities A, and the openings A when the latter are present, are filled, andfthe end walls of the element are thereby made sufficiently thick andgeneral manner in which the pad or washer parts C are welded in place.

In a preferred mode of forming an element in accordance with the present inven-.

tion I start with a seamless tube blank a usually of mild steel, and having a wall thickness and a length approximating that of the finished element. Such a tube may be twenty feet long with an external diameter of four and one-half inches and a wall thickness of threc-quarters of an inch. It will be understood, of course, that the foregoing di-' mensions are given by way of illustrative example, and that the invention is not limited to such tube blankdimensions. The tube blank a is first heated to bring one end approximately to a welding temperature, and the heated end is then expanded into the form shown in Fig. 5. In practice this end expansion maybe effected by what is essentially-a spinning operation, carried out by means of a rotating conical tool F forced into the end of the blank a while the tool is being rotated at a suitable speed. In practice the tool F may well be'coaxia-l with and removably carried by the rotatable head G of a machine of the type well known as a Van Stone machine. portion of the element has thus been enlarged, the end of the enlarged end portion 7 is more or less completely closed by the operation of suitable spinning tools which ma comprise a pair of tapered rolls FA shown in Fig. 6, and a second pair of rolls FB shown in Fig. 7 and operating on the tube end after the rolls FA have performed their function, the rolls FB being larger in diameter and more tapered than the rolls FA. The rolls FA and F B may well be successively mounted on the spindles G of the head G of the Van Stone machine. The end wall of the enlarged element end is then flattened as by pressing it against rolls FC journalled in bearings FC removably mounted onthe spindles G of the head G.

After the tube blank end is thus expanded and more or less closed, the enlarged end is off-set with respect to the body of the blank, and it and the portion of the blank body adjacent the expanded end are given their After an end' rectangular form. In thus shaping up the expanded end I advantageously first square the expanded and with a power hammer provided with work engaging parts H as shown in Fig. 9. If this unduly bulges the closed end as indicated in F ig.-9, the end flattening operation of Fig.

8 may then be repeated.

To off-set the :xpanded end and to give the rectangular fern. to the body of the blank,

are shaped by repeating the operations previously described.

7 After the blank is thus forged into shape, the cavities A and the opening A are filled with welding material, and the pad or washer parts C and the supporting parts Eare welded to the blank in the manner previously described. After the completion or in the course of the operations, the blank is subjected to the straightening operation above described when necessary, and the blank is heated and reheated as conditions make desirable at intervals as the various forging operations are being. carried out. Ordinarily, the openings A in the blank body and in the washer parts C of the element are reamed out to receive the tube connections B to be expanded in place therein after the forging,-shaping and welding operations are completed.

Instead of reducing the entire body of the blank to rectangular cross section as shown in Fig. 1, one or more intermediate portions of the blank body may be less flattened than the remainder of the blank body. For example, as shown in Fig. 11, a central portion A of the element AA is larger in the direction transverse to the heat absorbing face of the element than the major portion of the element body. This gives increased crosssectional area to the element channel in the portion A which may be desirable as for the application of a soot blowing attachment of certain type.

In forming elements in the manner described, the forging operations by which the body portion of each element is given its rectangular cross section are preferably car that elements having very difierent flowcapacities can be produced from the same standard blank with no change in the operations described above except in the extent to which the blank is flattened. For example, the element AB shown in Fig. 3A may be made from a blank identical in cross sect-ion with that from which the element A shown in Fig. 3 is made, and by following exactly, the-same steps except, that the body of the blank is flattened more in forging the body of the element AB than it is in forming the body of the element A. As shown, the cross sectional area of the channel A in the element AB is exactly one-half the cross sectional area of the channel A in the element A. Aside from the change in the channel cross sectional area, the effect of the increased flattening to which the blank form- A ing element AB is subjected, gives increased metal thickness"; at the corners of the element and makes the element channel less rectangular and more elliptical in cross section, but these changes in shape are of no particular consequence.

the elements A and AB may be, and in practice are ,produced from blanks of the same initial cross section. This capacity to produce elements of definitely different flow capacities from similar blanks and with practically no change in the operations required except in the extent of the flattening to which the bodies of the elements are subjected, constitutes an important practical advantage of the invention, and has the ultimate practical result of facilitating, and

cheapening the cost of production of radiant heat absorbing elements suitable for diflerent conditions of use,

The novel construction of av thick walled radiant heat absorbing element disclosed, but;

not claimed herein, is claimed in my prior application, Serial No. 177,796,flled March 23, 1927, of which this application is 'a division.

spirit of my invention as set forth in the appended claims, and that certain features of my invention may sometimes be used Numerous flow passage or ss sectional areas intermediate those of i with advantage without a correspondingiise of other features.

Having now described my invention what I claim' as new and desire to secure by Letters Patent, is

1. The method of forming a tubular fluid heating element having a plane surface adapted to absorb radiant heat which comprises expanding the end portions of a thick Walled tubular blank --of circular cross sec- -tion, compressing the end of said expanded end portions to substantially close the ends .of the element channel, closing the ends of said channel, applying welding material in molten form to thicken the end walls of said 'channel, and changing the cross sectional outline of said element from circular to rectangular.

2. In the method of forming a tubular fluid heating element having a plane surface adapted to absorb radiant heat, the step which consists in subjecting a thick walled A tubular blank of circular cross section tov forging and shaping operations giving it a rectangular outline in cross section.

3. In the method of forming a tubular fluid heating element having a plane/surface adapted to absorb radiant heat, the step which consists in symmetrically expanding end portions of a thick walled tubular blank.

4. In the method of forming a tubular fluid heating element adapted to absorb radiant heat, the step which consists in expanding end portions of a thick walled tubular blank of circular cross sectional outline and compressing the ends of said expanded end portions to substantially close the ends of the element channel.

5. In the method of forming a' tubular fluid heating element having a plane-surface adapted to absorb radiant heat, the steps which comprise expanding end portions of a thick walled tubular blank, compressing the-ends of said expanded end portions to substantially close theends of the element channel, completing the closure of the ends of said channel, and thickening the end Walls thereof by welding material applied to the element in a molten condition.

6. In forming tubular fluid heating elements adapted for the absorption of radiant heat and differing from one another in their channel cross sectional areas, the method 7 In forming a tubular fluid heating ele- 'ment having a plane surface adapted for the absorption of radiant heat, the method which comprises forming said element'from a thick Walled tubular blank of circular cross section by steps including the subjection of the blank to a forging operation converting its cross sectional outline into the form of a rectangle, the length of one side of which is approximately the same and but little less than the original blank diameter, While the length of the outer side of said rectangle depends on the desired cross sectional channel area of the element.

Signed at New York city, in the county of New York and State of New York, this 13th day of June, A. D. 1928.

' WALTER F. KEENAN, JR. 

